Carpenters calculating and lay-out tool



Dec. 13, 1955 L, yE, MAUP|N 2,726,452

CARPENTERS CALCULATING AND LAY-OUT TOOL Filed March 30, 1953 3 Sheets-Sheet l lll/ll llllll 28 INVENTOR eLfZz'eE. Mazzjvz'n ATTORNEYS Dec. 13, 1955 L, E MAUplN 2,726,452

CARPENTERS CALCULATING AND LAY-OUT TOOL Filed March so, 1953 :s sheets-sheet 2 Dec. 13, 1955 1 E. MAUPIN CARPENTERS CALCULATING AND LAY-OUT TOOL I5 Sheets-Sheet I5 Filed March 30, 1955 United States Patent() CARPENTERS CALCULATING AND LAY-OUT TOOL Leslie E. Maupin, Fort Lauderdale, Fla.

Application March 30, 1953, Serial No. 345,547

3 Claims. (Cl. 33-93) This invention relates to an improved calculating and lay-out tool especially designed for the use of carpenters in determining the lengths of roof rafters of various types, such as common, hip, valley and jack rafters; and for laying out the angles of the end cuts, and also other cuts thereof such as the plate notches, and the side cuts of the hip, valley and jack rafters.

The object of the invention is to provide a tool of the character above stated which shall be of few parts, and easy to operate to secure accurate results.

A tool of the type under consideration comprises generally a quadrant plate provided with various calculation tables and indicia, and having two straight ruling edges at right angles to each other; together with a straight bar pivotally mounted at the geometric center of the quadrant and having indicia thereon cooperative.

with said tables, as will be fully described hereinafter, and means for locking said bar in desired position. One of said straight edges is used as a guide for marking the bottom or level cuts of a rafter and the other side as a guide for marking the plumb or vertical cuts.

It will be obvious as the description proceeds, that the calculation tables must be based upon a series of index units of fixed value, such as lineal feet, so that the calculated result will be proportionate to the index unit used. However, it frequently occurs that the basic measurement upon which the desired result is to be determined includes a fraction of a unit between adjacent index units, so that a proportionate length must be added to the basic calculation to obtain the proper result.

A further object of the invention, therefore, is to provide the device with an odd-inch scale mounted upon said quadrant body and extendable laterally beyond the vertical edge thereof to complete the calculated measurement as indicated by the tables.

Other objects will appear hereinafter.

With the above objects in view, the device embodying the present invention comprises generally a flat quadrant plate having two straight ruling edges at right angles to 'each other, a straight bar pivotally mounted at the geometric center of said quadrant, cooperating indicia on said quadrant and said bar for calculating the length of rafter necessary for a given common run at various pitches, means for locking said bar at the angle of the desired pitch, and an auxiliary scale arm pivoted adjacent said geometric center and adapted to be extended at right angles to the adjacent edge of the quadrant for determining the additional length to be added to the length indicated by the tables, when the run is a fraction between indicia on the quadrant tables.

The invention further includes various cooperating indicia on the bar and quadrant for setting the bar to `obtain the proper angle of the plumb and level cuts of the various rafters; and also for the proper side cuts for the jack rafters and for the hip and valley rafters.

The invention will be more readily understood by reference yto the accompanying drawings, in which,

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Figure 1 is a plan view of a tool embodying the invention, the same being set, and illustrated in position on a timber for marking the level cut for the lower end of the rafter;

Figure 2 is a similar view with the tool in position for marking the plumb cut at the upper end of the rafter, and with the odd inch scale arm extended into position for use;

Figure 3 is an enlarged fragmentary sectional view, the section being taken through the pivot centers of the swingable bar and the odd inc scale arm;

Figure 3A is a similar section on the line 3A--3A of Figure l;

Figure 4 is a detail view, upon an enlarged scale,` of a portion of the device at and adjacent the geometric center of the quadrant, the upper portion of the swinging bar being removed;

Figure 5 is a face view of a portion of the quadrant upon a much enlarged scale, and illustrating the table for determining the lengths of hip and/or valley rafters required for a given rise or pitch;

'Figure 5A is a similar view of the remaining portion of the quadrant, and a portion of the swinging bar; and illustrating the table for determining the lengths of cornmon rafters required for a given run at specific pitches, together with indicia for setting the bar in position whereby the rafters may be marked for the level and plumb cuts at the ends of the rafters; also for the end cuts for hip and valley rafters; also for the side and level cuts for the hip and valley rafters; and for the side cuts of the jack rafters;

Figure 6 is a detail view of a form of the odd inch scale;

Figure 7 is a plan view of the pivot end of the swinging bar, viewed from the opposite side of the device than that shown in Figures 1 and 2;

Figure 7A is a similar view of the free or outer end of the bar, and

Figure 8 is a section on the line 8-8 of Figure 4.

Referring to the drawings, 10 indicates the quadrant,`

which is formed of a comparatively thin plate, having straight ruling edges 11 and 12 which are at right angles to each other, and an arcuate outer edge 13. Pivotally mounted on the quadrant 10 at the geomertic center 14 thereof, is a bar 15 consisting of a pair of substantially similar strips 16 and 17 which span and traverse-the opposite faces of the quadrant respectively. vThe ends of the strips 16 and 17 extend beyond the peripheral edge of the quadrant plate; and spacing members 18 and 19 are arranged between the adjacent projecting ends. Rivets 29, or other suitable means, secure the spacing member 18 in place between the adjacent strip ends; and a bolt 21 or other similar means, secures the spacer 19 in position. The longitudinal edges 22 and 23 respectively of the upper strip 16 are straight and parallel, as are also the corresponding edges 22 and 23' of the lower strip 17. At the geometric center of the quadrant 10, the bar 15, comprising the strips 16 and 17 is pivotally connected thereto by a pivot pin 25, the axis of which is in Valignment with the edge 22, said edge being provided with a laterally offset ear 26, and the quadrant having a similar ear 27, to receive said pivot pin. Adjacent the free end of the bar 15, the edge 22 of the strip 16 is provided with a laterally extending lug 28 which projects outwardly from said edge equidistant with the ear 26, so that when said lug and said ear engage the straight edge of a timber, the edges 22 and 23 will be parallel with said timber, the advantage of which will appear hereinafter. The pivot pin 25 extends through the ear 26 on the upper strip 16 of the bar 15 and the ear 27 of the'quadrant, and terminates in the plane of the lower face of the quadrant, as illustrated in Figure 8. Lugs 29 and 30 are provided on the edge of the quadrant in the path of the spacer member 18 to limit the throw of the bar 15.

The vertical, or plumb edge 12 of the quadrant 10 is laterally offset beyond the geometric center 14, forming a lateral extension 31 on the quadrant, and the outer portion of said extension is projected beyond the line of the upper edge 11, forming a lug 32 upon which the odd inch scale 33 is pivotally mounted as at 34. Between the ear 27 and the lug 32, the quadrant plate is formed with an inwardly extending notch or recess 35 into which the spacer 19 on the adjacent projecting end 15' of the bar 15, is received when said bar approaches the level edge 11 of the quadrant. The bar 15 is provided with a lock screw 36 threaded through the strip 16 and impinging against the quadrant adjacent the edge 13 thereof. By this construction both the bar 1S and the odd inch scale may be pivoted to the quadrant in the most eicient positions, and neither will interfere with the free operation of the other.

The face of the quadrant 10 is provided with various tables, which with cooperative indicia on the bar 15, will denote the various lengths of rafters required per run of common rafter at various degrees of pitch; and also the angle of cuts for various rafters.

In the drawings, 40 indicates the table for calculating or determining the lengths of cornrnon rafters, which includes an arcuate column 41 indicating the common run in lineal feet, and columns of figures extending radially from said foot run column 41 indicating the length of the roof rafters required for each unit of rise per foot. in Figure of the drawings this unit is in half inches from one and a half to nine inches per foot. The bar 15 is provided along the radial longitudinal edge 22 thereof, with indicia denoting various degrees of rise in inches per foot of run, and adapted to register with the figures in each of said radial columns, as illustrated in Figure 5A.

At 42 is indicated a similar table for hip and valley rafters, and further description thereof is unnecessary as it is similar in operation to the above.

Adjacent the periphery of the quadrant is an arcuate scale 44 indicating degrees from 0 to 90 which will be found valuable to artisans in various parts of their work. Radially inward from the degree scale 44 is a series of arcuate scales 46, 47, 48, 49 and 50 for setting the bar 15 in proper relation to the edges 11 and 12 of the quadrant, whereby the work may be readily and properly marked for cutting. Scale 46 is for setting the tool to indicate the bottom and plumb cuts for common rafters. Scale 47 is for the same use relative to the bottom cuts of hip and valley rafters. Scales 48 and 49 for jack rafters at different centers; and scale 50 is for polygon cuts for polygons having various numbers of sides. The scale 51 is for setting the device for the side cuts of hip and valley rafters; and scale 52 is for the side cuts of jack rafters.

The use of the device for determining the length of common rafters, and for obtaining the proper angles of the lower level and the top plumb cuts is as follows. The run of the rafter and also the pitch of the roof is known; and for the present description, the run is assumed to be eighteen feet. The bar 15 is moved over the cornmon rafter table 40 until the edge 22 thereof is in alignment therewith as illustrated in Figure 5A. The known -pitch of the roof is noted on the bar, and directly below this pitch index (say 5 inches to the foot) will be found the figures 19 feet, 6 inches. The bar is then moved until the edge 22 registers with the index 5 inches in the scale 46, and the screw 36 tightened to lock the bar in position on the quadrant. The device is then placed on the rafter with the edge 23 held rmly against the far edge thereof as illustrated in Figure 2, and a line a is drawn along the edge 12. This gives the plumb cut at the lower point of the rafter. Next, measure ott for the overhang, slide the tool up to this measure and again mark along the edge 12. The length of the rafter, ascertained as above described is then measured otf from this last mark. It should be noted here that the run of the rafter as indicated in the arcuate column 41 is given only in feet. Should the run be actually odd additional inches, the odd inch scale 33 is swung into position at right angles to the edge 12, as shown in Figure 2, and the additional distance, say 41/2 inches, is marked on the rafter as at b. The tool is then slid along the rafter until the edge 12 registers with the mark b and a vertical line drawn along said edge. As these measurements are based upon the full horizontal run, one-half of the thickness of the ridge timber should be deducted. This is easily accomplished by measuring back from the last mark b, along the scale 33 a distance equal to half the thickness of the ridge.

The next step is to mark for the notch to t over the plate. The workman then measures up on the second mark made (indicating the amount of overhang) and marks up in said lines the depth of the notch to be made. The tool is then slid along the rafter until the horizontal or level edge 11 registers with the inner end of said depth cut line, and the longitudinal cut is marked along said edge.

It is believed that the use of the tool for the various functions indicated by the several scales and tables on the quadrant and on the bar will be clearly understood by any master carpenter and that further description herein would be superuous. It is also obvious that the odd inc scale will be a great aid in marking off the stringers for stairways.

It is to be understood that in marking out the side cuts for hip, valley and jack rafters it is necessary to turn the tool over from left cut to right in order to obtain right and left cuts. This puts the strip 16 on the bottom side which has the lug 28 and ear 26 presented for engagement with the work. The strip 16 or 17 of the composite bar 15 which happens to be on the bottom side in the particular application of the tool always is the strip which engages the work, and this leaves the quadrant body on top of the timber to scribe by.

I claim:

l. In a device of the class described, a quadrant plate having a level ruling edge, a plumb ruling edge and an arcuate edge, a pivot pin on said plate with the axis thereof in alignment with said level ruling edge and at the geometric center of said arcuate edge, a bar pivotally mounted on said pin, one edge of said bar being in alignment with said axis of the pivot pin, arcuate scales and indicia on said plate with said axis of said pivot pin as the geometric center thereof, cooperating indicia on said bar, said bar consisting of a pair of similar strips spanning and adapted to traverse the opposite sides of said quadrant plate, both ends of each of said strips projecting beyond the peripheral edge of said plate, spacing elements fixed between the adjacent projecting ends, a scale arm pivotally mounted on said quadrant plate between said pivot pin for said bar and the plumb edge of said plate and adapted to be extended outwardly at right angles to said plumb edge.

2. ln a device of the class described, a quadrant plate having a level ruling edge and a plumb ruling edge at right angles to each other, and an arcuate edge, a pivot pin on seid plate with the axis thereof in alignment with said level ruling edge, and at the geometric center of said arcuate edge, a bar pivotally mounted on said pin, one edge of said bar being in alignment with said axis of the pivot pin, arcuate indicia and scales on said plate and concentric with said arcuate edge, cooperative indicia on said bar, said bar consisting of a pair of similar upper and lower strips spanning the opposite sides of said plate, respectively, both ends of said strips projecting beyond the peripheral edge of said plate, means fxedly connecting said ends, an ear projecting from the level ruling edge of said plate to complete the bearing for said pivot pin and a similar ear on the adjacent edge of the upper strip of the bar and registering therewith, and a lug on the same edge of said strip adjacent the free end thereof, said ear and said lug extending equidistantly from said bar.

3. In a device of the class described, a quadrant plate having a level rulingedge and a plumb ruling edge at right angles to each other, and an arcuate edge, a pivot pin on said plate with` the axis thereof in alignment with said level ruling edge and at the geometric center of said arcuate edge, a bar pivotally mounted on said pin, the edge of said bar adjacent said level ruling edge being in alignment with said axis of said pivot pin, arcuate indicia and scales on said plate concentric with said arcuate edge, cooperating indicia on said bar, said bar comprising a pair of similar upper and lower strips spanning the opposite sides of said plate respectively, both ends of said strips projecting beyond the peripheral edge of said plate, spacers fixed between the adjacent ends of said the plumb ruling edge of said plate, said plate having a notch extending inwardly from said level ruling edge between said pivotal connections as and for the purpose 10 described.

References Cited inthe le of this patent UNITED STATES PATENTS 944,799 Lytle Dec. 28, 1909 1,191,008 Laakkonen July 11, 1916 1,834,389 Drescher Dec. l, 1931 2,042,885 Fay June 2, 1936 

